From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Ooops on read-only raid5 while unmounting as xfs Date: Wed, 24 Jan 2007 10:54:12 +1100 Message-ID: <17846.40996.525616.51618@notabene.brown> References: <17845.25989.10063.901037@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from Francois Barre on Tuesday January 23 Sender: linux-raid-owner@vger.kernel.org To: Francois Barre Cc: linux-raid List-Id: linux-raid.ids On Tuesday January 23, francois.barre@gmail.com wrote: > > My question is then : what prevents the upper layer to open the array > read-write, submit a write and make the md code BUG_ON() ? The theory is that when you tell an md array to become read-only, it tells the block layer that it is read-only, and then if some process tries to open it read/write, it gets an array. I say "theory" because I have never really tested any of the read-only stuff. I have had a feeling for a long time that it really needs a bit of thought and testing and documentation, but it never quite seemed important enough to get that love-and-care.... NeilBrown